Institute of Organic Contaminant Control and Soil Remediation, College of Resource and Environmental Science, Nanjing Agricultural University, Nanjing 210095, PR China.
Institute of Organic Contaminant Control and Soil Remediation, College of Resource and Environmental Science, Nanjing Agricultural University, Nanjing 210095, PR China.
Chemosphere. 2022 Aug;301:134753. doi: 10.1016/j.chemosphere.2022.134753. Epub 2022 Apr 28.
The capability of laccase to oxidate a broad range of polyphenols and aromatic substrates in vitro offers a new technological option for the remediation of polycyclic aromatic hydrocarbon (PAH) pollution with high cytotoxicity. However, laccase application in the remediation of PAH-contaminated sites mainly suffers from a low oxidation rate and high cost because of the difficulty in its recovery. In this study, laccases were immobilized on magnetic FeO particles coated with chitosan (FeO@SiO-chitosan) to improve the operational stability and reusability in the treatment of PAH pollution. The enzyme fixation capacity reached 158 mg g, and 79.1% of free laccase activities were reserved under the optimum immobilized condition of 4% glutaraldehyde, 1.0 mg mL laccase, 2 h covalent bonding time, and 6 h fixation time. The degradation efficiencies of anthracene (ANT) and benzo[a]pyrene (B(a)P) by FeO@SiO-chitosan immobilized laccase in 48 h were 81.9% and 69.2%, respectively. Furthermore, it is very easy to magnetically recover the immobilized laccase from reaction systems and reuse it in a new batch. The relative activities of immobilized laccase were over 50% for the degradation of ANT and B(a)P in three catalytic runs, reaching the goal of substantially reducing cost in practice. According to the results from quantum calculations and mass spectrum analyses, the degradation products of ANT and B(a)P by laccase were anthraquinone and B(a)P-dione, respectively. The findings from this study provide valuable insight in promoting the application of immobilized laccase technology in the remediation of PAH contamination.
漆酶能够氧化体外广泛的多酚和芳香族底物，为具有高细胞毒性的多环芳烃（PAH）污染修复提供了一种新的技术选择。然而，由于回收困难，漆酶在 PAH 污染场地修复中的应用主要受到氧化速率低和成本高的限制。在这项研究中，漆酶被固定在壳聚糖包覆的磁性 FeO 颗粒（FeO@SiO-chitosan）上，以提高其在 PAH 污染处理中的操作稳定性和可重复使用性。在最佳固定条件（4%戊二醛、1.0 mg mL 漆酶、2 h 共价结合时间和 6 h 固定时间）下，酶固定容量达到 158 mg g，游离漆酶活性保留了 79.1%。FeO@SiO-chitosan 固定化漆酶在 48 h 内对蒽（ANT）和苯并[a]芘（B(a)P）的降解效率分别为 81.9%和 69.2%。此外，从反应体系中很容易通过磁性回收固定化漆酶，并在新批次中重复使用。在三个催化循环中，固定化漆酶对 ANT 和 B(a)P 的降解相对活性均超过 50%，达到了在实际应用中大幅降低成本的目标。根据量子计算和质谱分析的结果，漆酶降解 ANT 和 B(a)P 的产物分别为蒽醌和 B(a)P-二酮。本研究的结果为促进固定化漆酶技术在 PAH 污染修复中的应用提供了有价值的见解。
